In the field of photomechanical processing, it has been desired to use photographic light-sensitive materials excellent in original reproducibility, stable processing solutions and simplified replenishment methods to cope with diversification and complexity of printed material.
In particular, line originals to be subjected to the process of picture taking normally comprise photo-composed letters, handwritten letters, illustrations, dot photographs, etc. Thus, line originals are normally formed of a mixture of images having different densities and line widths. Therefore, the ability to provide plate-making cameras, photographic light-sensitive materials or image formation methods which can give an excellent reproduction of these originals have been sought.
On the other hand, enlargement or reduction of dot photographs is widely conducted to make plates for catalogues or large-sized posters. In the dot enlargement process, the number of lines per square inch decreases, giving an unsharp picture. In the dot reduction process, the number of lines per square inch becomes greater than that of the original, giving a fine picture. Accordingly, an image formation method has been desired which provides a wider latitude to maintain an excellent reproducibility of dot gradation.
As a light source for plate-making cameras, halogen lamps or xenon lamps have been employed. In order to be sufficiently sensitive to these light sources, light-sensitive materials are normally subjected to orthochromatic sensitization. However, it has been found that photographic light-sensitive materials which have been orthochromatically sensitized are more susceptible to effects of chromatic aberration of the lens which can deteriorate the picture quality, particularly when a xenon lamp is used.
In a known method for meeting the demand for wide latitude, a lithographic silver halide photographic material comprising silver bromochloride (at least having a silver chloride content of 50% or more) is processed with a hydroquinone developer having an extremely low effective concentration of sulfurous ions (normally 0.1 mol/l or less) so that line originals or dot images having a high contrast and blackened density on the image portion and the nonimage portion are definitely distinguished from each other. However, this method is disadvantageous in that the development is extremely unstable to air oxidation due to the low sulfurous acid concentration of the developer. In order to stabilize the activity of the developer, various efforts and measures must be made. Furthermore, this method provides a remarkably low processing speed, lowering the working efficiency.
Thus, an image formation method has been desired which encompasses development with a processing solution having an excellent storage stability to provide an ultrahigh contrast while eliminating the instability in the formation of images by the above mentioned development method (lithographic development system). In a system as proposed in U.S. Pat. Nos. 4,166,742, 4,168,977, 4,221,857, 4,224,401, 4,243,739, 4,272,606, and 4,311,781, a surface latent image type silver halide photographic material comprising a specific acylhydrazine compound is processed with a developer with a pH value of 11.0 to 12.3 containing 0.15 mol/l or more of a sulfurous acid preservative and having an excellent storage stability to form an ultrahigh contrast negative image where .gamma. is more than 10. This new image formation system is characterized in that it can use silver bromoiodide and silver bromochloroiodide while the prior art ultrahigh contrast image formation systems can use only silver bromochloride having a high silver chloride content.
The aforementioned image formation system is adequate in view of dot sharpness, processing stability and rapidity, and original reproducibility. However in order to cope with the recent diversification of printed matters, a system has been desired which provides a greater stability and higher original reproducibility.
A light-sensitive material comprising a redox compound which undergoes oxidation to release a photographically useful group is disclosed in JP-A-61-213847 (the term "JP-A" as used herein means an "unexamined published Japanese patent application") and 64-72140, and U.S. Pat. No. 4,684,604. A system using silver bromochloride is disclosed in JP-A-60-83028, 60-112034, 62-235947, and 63-103232. These proposals are intended to widen the reproduction range of gradation. However, in an ultrahigh processing system using a hydrazine derivative, such a redox compound inhibits the improvement of contrast, making it impossible to make use of the features of the system.
In a silver halide photographic material which comprises hydrazines, the percent swelling has a great effect on the photographic properties as disclosed in JP-A-62-237444, 63-96033 and 1-187542.